Austral Spring Stratospheric and Tropospheric Circulation Interannual Variability

Abstract

The relationship between the October (spring) total ozone column (TOC) midlatitude zonal asymmetry over the Southern Hemisphere (SH) and the stratospheric quasi-stationary wave 1 (QSW1) interannual phase variability is analyzed. Once contributions to the TOC from known global predictors, estimated with a multiregression model, are removed, the residual TOC interannual variability is observed to be dynamically coupled to the stratospheric QSW1 phase behavior. The stratospheric QSW1 interannual phase variability, when classified according to specifically designed indices, yields different circulation patterns in the troposphere and stratosphere. High (upper quartile) index values correspond to a westward rotation of the midlatitude ozone trough and the stratospheric QSW1 phase, while low (lower quartile) index values represent their eastwardrotated state. These values can be associated with statistically different tropospheric circulation patterns: a predominantly single poleward tropospheric jet structure for high index values and a predominantly double-jet structure for low index values. For the latter, there is a higher daily probability of double-jet occurrence in the troposphere and a stronger stratospheric jet. These jet structures and their daily behavior are supported by significant synoptic-scale activity anomalies over SH mid-to high latitudes as well as changes in tropospheric quasi-stationary waves 1-3. The wave activity flux (W flux) diagnosis shows the contribution of active quasistationary waves in the observed tropospheric anomalies associated with high and low index values. With low index values, the quasi-stationary waves lead to a self-sustaining state of the stratospheric-tropospheric coupled system. With high index values, the overall mid-to high latitude circulation is associated with wave energy propagation from the tropical central Pacific into higher latitudes. Thus, during the austral spring, there are interactions between the troposphere and stratosphere, leading to the locally well-defined upward and downward propagation of wave anomalies, that is, significant upper troposphere (UT)-lower stratosphere (LS) interactions can occur within a spring month itself.

Evolution of the eastward shift in the quasi-stationary minimum of the Antarctic total ozone column

“…Previous studies have revealed the tendency of the Antarctic polar vortex to exhibit an eastward shift in orientation (Huth and Canziani, 2003), in the ozone minimum location (Grytsai et al, 2005;Malanca et al, 2005;Grytsai et al, 2007a, b;Canziani, 2010, 2011;Grytsai, 2011;Hassler et al, 2011) and in the phase of wave 1 in stratospheric temperature (Lin et al, 2010). This eastward shift has been described as possibly connected with a change in tropospheric stationary waves (Grytsai et al, 2007a), tropospheric jet structure (Hio and Hirota, 2002;Agosta and Canziani, 2011) and its strengthening (Wang et al, 2013), and stratospheric ozone and volcanic aerosol concentration (Lin et al, 2010). The quasi-stationary wave (QSW) activity increases typically in austral spring (Randel, 1988), and its enhancement leads to larger vortex asymmetry, a decrease in ozone hole area and net stratospheric ozone loss.…”

“…In spring, the ozone distribution in the Antarctic region is asymmetrical with a maximum in the Australian longitudinal sector and a minimum in the Atlantic longitudes (Grytsai et al, 2005;Agosta and Canziani, 2011). Previous studies have revealed the tendency of the Antarctic polar vortex to exhibit an eastward shift in orientation (Huth and Canziani, 2003), in the ozone minimum location (Grytsai et al, 2005;Malanca et al, 2005;Grytsai et al, 2007a, b;Canziani, 2010, 2011;Grytsai, 2011;Hassler et al, 2011) and in the phase of wave 1 in stratospheric temperature (Lin et al, 2010).…”

Quasi-stationary planetary waves in late winter Antarctic stratosphere temperature as a possible indicator of spring total ozone

“…It is known that a climatological east-west asymmetry of the Antarctic polar vortex and ozone hole exists with a typical displacement from the South Pole toward the Atlantic sector, 0 • -60 • W (Wirth, 1993;Waugh and Randel, 1999;Grytsai et al, 2007;Agosta and Canziani, 2011). Figure 6 illustrates the changes in the TOC field asymmetry in August under conditions of the strong polar vortex in 2006 (Fig.…”

Observation and simulation of wave breaking in the southern hemispheric stratosphere during VORCORE

“…2a), indicating that the observed wave is the QSW1. This wave has high amplitude in the stratosphere and dominates by far the flow in the Southern Hemisphere during spring (Agosta and Canziani, 2011;Hartman, 1977;Randel, 1988;Moustaoui et al, 2003b).…”

“…The wind along its edge presents little variations in the zonal direction. In spring, however, the SH stratospheric circulation is by far dominated by the quasi-stationary planetary wave with the zonal wavenumber 1 (QSW1) (Geller and Wu, 1987;Wirth, 1991;Bowman, 1993;Agosta and Canziani, 2011;Hartman, 1977;Randel, 1988;Moustaoui et al, 2003b). The QSW1 causes the vortex to be displaced from the pole or even split.…”